2020 Volume 62 Issue 2 Pages 257-281
I began my career with the Geology Laboratory of the Railway Technical Research Institute of the Japan National Railways. Most of my jobs for more than 55 years since then are related to tunnel construction, especially with difficulties arisen from groundwater inflow. As I had the opportunity to present the article for the special issue 'Tunnel' of the Journal of Groundwater Society, essences of what I have learned and experienced with regard to groundwater inflow to tunnels are introduced with some of the case studies. Firstly, an overview on the "Fundamentals of groundwater inflow" is explained, such as classification and treatment of water inflow, concept of perpetual water inflow in tunnel with its origin, and the reason why difficulties of tunnel construction is proportional to the amount of water inflow and level of ground pressure. Then, various findings through my research on water inflow and tunnels are introduced, such as systemization of hydrological survey methods, how to select tunnel route, construction methodology of tunnel and effective use of tunnel water inflow, interrelation between tunnel and dam when constructed adjacent to dam, and water quality of tunnel inflow. I hope this article may be helpful to those researchers and engineers involved in tunnel construction.
